Apparatus and method for handling and treating articles

ABSTRACT

Improved apparatus and method for transporting articles and for centering articles in sequence by means of fluid-bearing devices. The apparatus and method disclosed have particular utility in the handling and treatment of fragile articles, such as silicon wafers, but their utility is not restricted to such use. After centering, the articles are transferred by vacuum means to a spinning unit at which the articles are treated, as by coating the same with a liquid product, such as a photoresist material. Transfer from the spinning unit is by vacuum means. In a substantially continuous procedure, articles to be treated are withdrawn in sequence from a supply magazine by fluid-bearing structure, moved through the centering and treating steps, and deposited in a discharge magazine by fluid-bearing structure without manual handling during the procedure. The fluid-bearing structure of an alternative embodiment is provided with bidirectional capability.

United States Patent Lasch, Jr. et a1. Feb. 29, 1972 [54] APPARATUS ANDMETHOD FOR 3,103,388 9/1963 Cole ..302/31 HANDLING AND TREATING ARTICLES18,640 5/1967 Coville.... ..302/31 v 3,319,856 5/1967 Stanley ..302/31[72] lnventors: Cecil A. Lasch, Jr., Mountain View;

George H. Bingham, Los Altos; Gerhard Prim ry ExammerEvon C. Blunk B 212 Earl Troyer Cuper' Assistant ExaminerW. Scott Carson a 0 canAttorney-Flehr, Hohbach, Test, Albritton & Herbert [73] Assignee:Industrial Modular Systems Corporation,

Cupertino,'Ca1if. [57] ABSTRACT [22] Filed; Nov. 26, 1968 Improvedapparatus and method for transporting articles and I for centeringarticles in sequence by means of fluid-bearing Appl' 779033 devices. Theapparatus and method disclosed have particular utility in the handlingand treatment of fragile articles, such as 521 05.0. ..302/2 R, 198/19,1922/ R, silicon wafers, but their utility is not restricted to such use214/164 R, 221/88, 302/] 1, 302/31, 214/] 31 After centering, thearticles are transferred by vacuum means [51] Int. Cl ..Bg 51/02, 365g60/00 a to a pi n g i at which the articles are r as y coat- [58] FieldoiSearch ..302/29,31,2,11;221/81, ing he Same i a iq i pr d t, u h a aphotoresist 221/236, 278, 88; 271/74; 198/19, 20; 214/164 R, material.Transfer from the spinning unit is by vacuum means.

1 ET in a substantially continuous procedure, articles to be treated arewithdrawn in sequence from a supply magazine by fluid- [56] Referencescued bearing structure, moved through the centering and treating UNITEDSTATES PATENTS steps, and deposited in a discharge magazine byfluid-bearing structure without manual handling during the procedure.The 3,222,110 12/1965 Kelly et al ..302/2 fl id b i Structure f analternative embodiment i 2,778,691 1/ 1957 Hazel ....302/2 vided withbidirectional capability 2,801,884 8/1957 Friedman. ...302/2 2,842,9237/1958 Kjellsen ....302/2 52 Claims, 20 Drawing Figures Patented. Feb.29, 1972 8 Sheets-Sheet 2 m (Feb. 29, 1-912 Avwwrae: (rm 4. [456169/2VIZ Patented Feb. 29, 1972 3,645,58

v 8 Sheets-Sheet 8 I APPARATUS AND METHOD FOR HANDLING AND TREATINGARTICLES BACKGROUND OF THE INVENTION tions at which various operationsare performed thereon in 'articles and, when such means is incorporatedinto an integrated apparatus, for centering such articles to facilitatesubsequent treatment thereof. In an alternative embodiment, suchfluid-bearing means includes bidirectional capability to 'permitselective movement of the articles in two directions relative to apredetermined location.

This invention furthermore relates to improved supply magazine anddischarge magazine structure from which, and into which, articles may beautomatically unloaded and loaded by fluid bearing means associatedtherewithnMagazine indexing means is provided in conjunction with theout-feed and infeed fluid-bearing structures.

This invention also relates to an improved mechanism for coatingarticles,.such as fragile silicon wafers, with a fluid material, such asa photoresist material known and heretofore used in the electronicsindustry in the manufacture of components above noted.

In its broader aspects, this invention relates to means and proceduresfor handling articles of various types by means of improvedfluid-bearing structures for performing various functions on'sucharticles, such as for moving the same from one point to another or forcentering the same in preparation for subsequent treating operations.

In Jitsmore specific aspects, this invention relates to improvedfluid-bearing'wafer transporting means and fluid-bear- :ing'wafercentering means, combined with wafer supply magazine and dischargemagazine structures which are automatically indexed to permit out-feedand infeed therefrom, coupled with vacuum transfer mechanisms and awafer coating unit to provide an integrated wafer handling and coatingapparatus and procedure.

Description of The Prior Art In the electronics industry, mechanisms forapplying a liquid coating, such as a photoresist material, to anarticle, such as a silicon wafer, have been generally known heretofore.However, with prior known coating procedures, articles to be treatedgenerally have required manual handling, normally by using vacuum pickupdevices or tweezers, usually in a one-atmanually, thereby eliminatingintermediate manual handling to facilitate manufacture of articles, suchas electronic com- 65' ponents, and thereby speed up their manufactureand reduce their unit cost.

Fluid-bearingdevices of various types have been generally knownheretofore, and the following US. Pats. Nos. disclose devices which areexemplary of the prior art: Hazel 2,778,691 dated .Ian. 22, 1957; Cole3,103,388 dated Sept. l0, 1963; and Coville 3,318,640 dated May 9, I967.Prior known fluid-bearing structures of the type exemplified by thesepatents, however, do not contemplate or disclose the improved bearingfeatures disclosed hereinafter.

Furthermore, while fragile articles, such as silicon wafers, have beentransported in groups in magazines to protect such articles prior to orafter treatment thereof, heretofore, loading and unloading of suchmagazines has been manually effected, .such as by vacuum, tweezers orother suitable devices. So far as is known, the novel arrangementdisclosed herein of employing fluid-bearing means to automaticallyunload or load articles, such as silicon wafers, into supply ordischarge magazines has been unknown. The savings and convenience ofsuch a handling procedure is very important in a fragilearticle-handling operation because of the virtual elimination of thedanger of breakage of such articles which has been frequentlyencountered in prior manual handling operations.

Furthermore, with heretofore known procedures for treating siliconwafers in the electronics industry to coat the same with a photoresistmaterial or the like, manual operations have been employed to place thearticles on the spindle of a spinning device. Such manual operationsrequired a value judgment as to whether the articles were properlycentered on the spindle prior to rotation of the same. Such judgmentfrequently was inaccurate, because of understandable human error,thereby resulting in nonuniform coating or breakage. The presentinvention includes fluid-bearing means for automatically centeringarticles prior to their being placed on a rotating spindle so thatproper article positioning is assured.

The numerous advantageous features of this invention are incorporatedinto a compact table-top supportedmachine in the embodiment illustrated.However, it should be understood that the respective inventive featuresdisclosed herein also have applicability and utility independently ofeach other and in otherhandling and treating environments apart from theexemplary wafer-handling procedure disclosed herein.

SUMMARY OF THE INVENTION The present invention relates to an apparatusand method for handling and treating articles. The invention asspecifically disclosed herein relates to an apparatus and method fortransporting fragile articles, such as silicon wafers, from one locationto another during processing of such articles. Still more particularly,this invention relates to an apparatus-and method in which articles,such as silicon wafers, are automatically fed from a supply source, suchas from asupply magazine, and transported to a centering device; aftercentering, the articles are transported to a treating unit where thesame are treated, such as by coating the same with a fluid material,such as a photoresist material; following such treatment, thearticlesare transported from the treating unit and are discharged, suchas by loading the same automatically into a discharge magazine. All suchoperations are effected in sequence without requiring any intermediatemanual handling.

- In the apparatus illustrated herein, the various novel aspects of thisinvention are incorporated into a single machine capable of handlingarticles of varying sizes without requiring adjustment or-modificationsof the machine components. Silicon wafers commonly employed in theelectronics industry for numerousknown purposes are typical of thevariable size articles which maybe handled with the apparatus disclosed.However, utilization of the various novel features of this invention inother fields of endeavor is contemplated within the scope of thisinvention.

Specifically, novel improved fluid-bearing means preferably are used totransport articles in this invention, as well as to center such articleswhen centering is required in a given treating procedure. Theutilization of improved fluid-bearing track structure to withdrawarticles in sequence from a source of supply, such as a supply magazine,or to insert such articles into a discharge station, such as a dischargemagazine, without manual handling is an important feature of thisinvention and has applicability inareas other than wafer handling. lnconjunctionwith such magazine out-feed or infeed procedures, magazineindexing mechanisms are provided.

The air-bearingcentering unit, and the air-bearing track structuredisclosed herein, are provided by structures which,

'IOIOZS 0047 respectively, insure proper centering of articles of widelyvarying types and sizes fed thereto in sequence, and effectivetransportation of such articles relative to a reference location, eitherin a single directional or in a bidirectional relationship.

From the foregoing, it should be understood that objects of thisinvention include: the provision of improved fluid-bearing means forhandling articles of various types and varied sizes; the provisions ofimproved fluid-bearing means particularly well suited for handlingfragile articles, such as silicon wafers; the provision of means forcentering articles of various types and varied sizes by utilizingfluid-bearing structure to effect centering; the provisions of improvedtreating means for coating articles, such as silicon wafers, andtransfer mechanisms for introducing into and removing articles from suchtreating means; the provision, in combination, of fluid-bearing meansfor removing articles from or introducing articles into magazines orother reference stations; the provision of an improved mechanism forautomatically indexing supply or discharge magazines to permit articlemovement relative thereto; the provisionof an overall apparatus andmethod for automatically transferring articles, such as silicon wafers,

through a series of steps without intermediate manually handlingthereof; and the provision of an apparatus and method for handling andtreating in sequence a series of articles, such as silicon wafers, towithdraw the same from a supply magazine or other source of supply,center the same, place the same on a spinning unit on which the same arecoated with a material such as a photoresist material, to remove thearticles from the spinning unit, and to insert the same into a dischargemagazine.

These and other objects of the overall combination and subcombinationsof novel features disclosed herein will become apparent from a study ofthe following detailed disclosure in which reference is directed to theattached drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic flow diagram of thehandling and treating procedure effected by the subject apparatus.

FIG. 2 is a plan view of the apparatus.

FIG. 3 is a side elevational view of the apparatus taken in the plane ofline 3-3 of FIG. 2.

FIG. 4 is a partial plan view of the centering unit and outfeedfluid-bearing track structure taken in the plane of line 5-5 of FIG. 4-.

FIG. 6 is a vertical sectional view through the out-feed fluidbearingtrack structure taken in the plane of line 6-6 of FIG. 4.

FIG. 7 is a vertical sectional view through the track structure taken inthe plane of line 7-7 of FIG. 6.

FIG. 8 is a vertical sectional view through a bar of the track structuretaken in the plane of line 8-8 of FIG. 7.

FIG. 9 is a vertical sectional view through the centering unit taken inthe plane line 9-9 of FIG. 3.

FIG. 10 is a partial plan view through the apparatus taken in the planeof line 10-10 of FIG. 9.

FIG. 1 l is a vertical sectional view through the spinning unit of theapparatus taken in the plane of line 1 1-1 1 of FIG. 2.

FIG. 12 is a horizontal sectional view through a portion of theapparatus taken in the plane of line 12-12 of FIG. 3.

FIG. 13 is a side elevational view of that portion of the apparatusshown in FIG. 12 taken in the plane of line 13-13 of FIG. 12.

FIG. 14 is a partial plan view of the infeed fluid-bearing trackstructure taken in the plane of line 14-14 of FIG. 3.

FIG. 15 is a vertical sectional view through the infeed track structuretaken in the plane of line 15-15 of FIG. 14.

FIG. 16 is a horizontal sectional view through the infeed trackstructure taken in the plane of line 16-16 of FIG. 15.

FIG. 17 is a plan view of an alternative fluid-bearing track structurehaving bidirectional capability.

FIG. 18 is a vertical sectional view through the 'altemative embodimentof FIG. 17 taken in the plane of the line 18-18 of FIG. 17.

FIG. 19 is a vertical sectional view through the alternative embodimentof FIG. 17 taken in the plane of line 19-19 of FIG. 18.

FIG. 20 is a schematic view of the valve control arrangement employedwith the preferred embodiment of the apparatus illustrated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As noted previously, theapparatus and method of this invention are disclosed herein withparticular reference to the handling, transporting, and treatment ofarticles, such as thin, fragile silicon wafers of the type widely usedin the electronics industry. However, it should be understood that useof the novel combination and subcombination invention is not restrictedto the particular exemplary showing contained herein but that suchfeatures are readily adaptable for use in other fields in the handling,transporting or treating of various and varied articles. It should alsobe understood that the various features of this invention, while highlyeffective when combined to provide an integrated apparatus such as thatdescribed, have applicability independently of each other in thehandling and treatment of articles as disclosed herein as well asothers.

SUMMARY OF OPERATION Referring first to the schematic showing of FIG. 1,the sequence of treatment of a series of articles, such as theexemplarly thin silicon wafers in preparation of the same for subsequentuse and transformation into integrated circuits, transistors, and thelike, will be described. A quantity of such wafers (each designated W inthe drawings) numbering 20 or more, have been previously positioned in asupply magazine I in any known fashion. The wafer filled magazine 1 ismanually or otherwise positioned at a feed station at which the magazineis vertically indexed in step fashion to present individual waferssequentially at an out-feed position. Wafer withdrawing out-feed andtransfer means, generally designated 2, in the form of a fluid-bearingtrack structure, preferably of the pneumatic type, removes individualwafers in sequence from the supply magazine and transfers the same to acentering unit, generally designated 3, positioned at an adjacentcentering station. The centering unit comprises fluidbearing structure,preferably of the pneumatic type, in which the wafers presented theretoin sequence have their centers located and oriented in a predeterminedposition, such position being maintained positively by pickup andtransfer means, generally designated 4, during transfer of the wafersfrom the centering station.

The transfer means 4, preferably of the vacuum arm type, picks up andtransports the wafers in sequence from the centering station to anadjacent treating station. At the latter station, a treating operationis performed on each successive wafer by a spinning and coating unit,designated 6. Such treating operation in the disclosed embodimentcomprises a coating step performed by spinning each wafer as a measuredquantity of fluid material, such as a photoresist liquid, is appliedthereto and spread thereover by centrifugal force during spinning.

Following such coating, the wafers are picked up in sequence andtransported by second pickup and transfer means, generally designated 7,which also preferably is of the vacuum arm type, toward a waferdischarge station. Such transfer means places the wafers in sequence onother transfer and infeed means, generally designated 8, providedadjacent the discharge station. The infeed means, in the form of afluidbearing track structure, preferably of the pneumatic type, movesthe wafers in sequence to the discharge station.

At the discharge station, a discharge magazine 9 is positioned toreceive the coated wafers therein for subsequent transfer'as a group(manually or otherwise) to other treating stations during theirsubsequent transformation into electronics components. The dischargemagazine is vertically indexed in step fashion to receive individualwafers presented thereto in sequence by the infeed fluid-bearing trackstructure 8.

Upon emptying of all untreated wafers from the supply magazine 1 andfilling of the discharge magazine 9 with treated wafers, new supply anddischarge magazines are positioned in the apparatus and the cycle ofoperations described is repeated.

Details of the various cooperating componentsand units of the apparatuswill now be described.

WAFER SUPPLY MAGAZINE STRUCTURE AND INDEXING MEANS Reference is directedto FIGS. 1 through 6 for an illustration of the components of theapparatus employed at the wafer feed station. As mentioned previously,at such station is provided a wafer supply magazine 1 in which arepositioned a plurality of wafers, the number of which is determined bythe magazines size, which may be varied to meet particular needs. In theillustrated embodiment, the magazine has space provided therein toreceive 20 wafers vertically spaced one above the other.

The supply magazine comprises a body 11 formed of suitable plastic, suchas nylon or Teflon, having a generally U- shaped configuration inhorizontal cross section as best seen in FIG. 2. The magazine body isprovided with a generally Y- shaped cutout portion 12, through whichwafers are inserted or removed during loading or unloading of themagazine. Communicating with the cutout portion and defining the sameare a series of parallel vertically spaced lips 13, best seen in FIGS.and 6, which define therebetween a series of vertically spaced slots 14in which the supply of wafers W is received.

As noted from FIGS. 2 and 4, slots 14 between the adjacent lips areprovided with straight, generally parallel side faces connected witheach other by a generally arcuate end face. The width and height of therespective slots is substantially greater than the size of the wafersshown positioned therein, sov that wafers of varying sizes may beaccommodated in the magazine. It should be noted that the Y-shapedcutout portion 12 of the magazine extends substantially to the end faceof the respective slots, as seen in FIG. 2, so that the cutout portionunderlies substantially the entire surface of each wafer carried in thesupply magazine. Such wafers are supported along opposite edges thereofby their engagement with the respective lips T3 of the magazine but aregenerally free of support throughout their central sections.

As the magazine is indexed in step fashion by the indexing means to bedescribed, successive wafers are automatically fed from the magazine bythe withdrawing out-feed means to be disclosed. The magazine indexingmeans in the preferred embodiment illustrated includes a support base 16for the magazine (FIGS. 2 and 3). Pivotal lock structure for themagazine, generally designated 17, is provided in conjunction with thesupport'base. Such lock structure comprises an elongated pin 18,extending through a bore 19 in the support base, having a locking cam 21on its inner end and a manually operable handle 22 on its outer end. Thebase of the supply magazine is provided with an opening 23 therein inwhich the locking cam is receivable when handle 22 is pivoted to theupper locking position shown in FIG. 3. Thus, when a magazine ispositioned on the support base and is properly oriented thereon, thehandle 22 is rotated to the upper position to engage the locking cam 21with the magazine and to hold the magazine securely in place and inproper orientation for feeding of wafers therefrom. It should beunderstood, of course, that the support base has a slot therethrough inwhich the locking cam 21 is movable between its respective locked andunlocked positions of engagement with the magazine.

As noted from FIG. 2, support base 16 is defined by a generallyrectangular plate having a planar upper surface from which spacedshoulders 24 project upwardly to define therebetween a magazinereceiving slot. The shoulders include opposed outwardly diverging faces26 which terminate in generally straight parallel faces 27, the latterof which are engaged by the outer parallel sidewalls of the magazinewhen a magazine is positioned on the support base. The diverging faces26 facilitate proper insertion of the magazine into its wafer out-feedposition.

The shoulder portions of the support base are provided with parallelvertical bores 28 through which guide structure for the supportbaseextends. Such guide structure in the embodiment illustrated comprises apair of spaced circular cylindrical rods 29 along which the support base16 is slidable during vertical indexing movement of the supply magazine.Guide rods 29 in turnare secured to and supported in rigid upstandingrelationship by a main base plate 31 of the supporting framework of theapparatus as seen in FIG. 3. Such guide rods may be threadedly engagedwith the base plate 31 or otherwise suitably secured thereto at one endthereof. Preferably, bearings 32 are positioned in bores 28 and surroundthe guide rods as seen in FIG. 2 to facilitate indexing movement of thesupport base. Such bearings are held in place in the bores of theshoulder portions of the support base by capscrews 33, positioned toextend through and draw together adjacent spaced portions of the baseplate shoulders which are separated by adjustment permitting slots 34,as seen in FIG. 2.

Vertical movement of the support base 16 and the supply magazinetherewith in the illustrated embodiment is effected by amovable rod 36which is actuated in predetermined vertical increments by a suitablepower source or drive mechanism to be described. In the preferredembodiment illustrated, the movable rod is operatively engaged with thesupport base so that movement of the rod effects vertical movement ofthe support base. To that end, a threaded bore 37 is provided in thesupport base adjacent one of the guide rods 29 therein and rod 36 incorrespondingly threaded for substantially its full length. Thus,support base 16 and the supply magazine carried thereby are moved in apredetermined direction, either upwardly or downwardly as desired, inaccordance with the direction of rotation of the movable rod 36. Withthe illustrated construction, rotation of rod 36 one revolution efiectsvertical indexing of the associated magazine an increment equal to thedistance between adjacent slots 14 in the magazine. Of course, otherrelationships may be employed if preferred.

While various power source drive mechanisms may be employed to move therod 36, such as hydraulic or pneumatic mechanisms, in the preferredembodiment illustrated herein, an electromechanical mechanism isemployed, namely a servomotor 38 of known type secured in dependingrelationship by means of a series of bolts 39 from the under surface ofthe main base plate 31 of the apparatus. A flexible coupling 41operatively connects the servomechanism of the motor 38 with the movablerod 36 in known fashion to effect rotation of the rod in predeterminedincrements (preferably one revolution per indexing step, as notedpreviously) in response to signals received by the motor from a suitablecontrol source following movement of each wafer in sequence from thesupply magazine. That is, rod 36 is rotated sequentially by theservomotor in amounts sufficient to move the supply magazinesequentially the distance of the spacing between adjacent slots 14 inthe magazine so that successive wafers are presented at a waferwithdrawing position.

In that connection, upon initial operation of the apparatus with afilled supply magazine placed on the support base 16, the lowermostwafer in the magazine is first withdrawn and the support base, with themagazine thereon, is indexed vertically downwardly in step fashion topresent each successive lowermost wafer to the withdrawing positionuntil the supply magazine is empty, at which time suitable control meansinterrupts further operation of the withdrawing procedure until thesupport base is relocated in the upper position and another filledmagazine is positioned on the support base.

Referring to FIGS. 2 and 4, indexing sequence control signalsaretransmitted to the servomotor 38 from a control source locatedadjacent the feed station. The control source preferably comprises alight source which is interrupted by each successive wafer passing fromthe supply magazine. Such light source in the preferred embodiment, asseen in FIG. 2, preferably comprises a fibre-optic sensor 46 positionedadjacent the supply magazine and supported by the wafer outfeed andtransfer means to be described. As the leading edge of each waferwithdrawn from the supply magazine passes over the sensor 46, theinterruption of light passage to the sensor transmits a signal in knownfashion to the motor 38. This first signal is disregarded by the motor,through use of suitable and conventional control devices provided aspart of the overall electronic control of the apparatus. Howevenas thetrailing edge of each wafer clears the sensor, a second signal istransmitted to the motor, in response to which the motor is actuated inknown fashion to effect rotation of the drive rod 36 one revolution toeffect downward indexing of the supply magazine one step to bringanother wafer into its out-feed position. Such second signal alsointerrupts flow of wafer supporting fluid until indexing and wafercentering are completed, as will be described. Details of thefibre-optic sensor utilized have not been disclosed herein because sucha device, and its control relationship to a power drive sourcemechanism, such as a servomotor, and a fluid valve, are well known inthe control art.

Also provided in conjunction with the supply magazine indexing means areother control means for permitting the initiation of the indexingoperation and termination thereof automatically when the supply magazineis empty. In that regard, referring to FIG. 3, upper and lower limitswitches, designated 47 and 48 respectively, are supported in anysuitable fashion on the apparatus framework adjacent a guide rod 29 atone side of the apparatus. In the embodiment illustrated, such limitswitches are adjustably positioned to project from one of a pair ofspaced upright mounting plates 49 projecting upwardly from the main baseplate 31 of the apparatus Secured in depending relationship from thebase support 16 is a switch actuator 50 shown intermediate its upper andlower extremes of travel in FIG. 3.

When the base plate 16 is raised toward its uppermost position with afull magazine positioned thereon, switch actuator 50 engages the togglearm 51 of switch 47 which transmits a signal in known fashion to themotor 38 to preclude any further upward movement of the base plate. Inthis position, the bottom slot of the supply magazine is located oneindex increment above the lowermost wafer withdrawing position.

When the switch actuator 50 is carried with the support base to itslowermost position in which the last wafer has been withdrawn from themagazine, the toggle arm 52 of the lower limit switch is engaged and asignal is transmitted to motor 38 in known fashion to preclude anyfurther downward movement of the support base 16, thereby effectivelyshuting off the wafer out-feed operation until the support base isrepositioned and a filled magazine is located in place of the emptymagazine. Repositioning of the support base may be effected by asuitable override control (not shown) which effects reverse operation ofthe servo motor and drive rod 36 associated therewith until switchactuator 50 contacts the upper limit switch arm 51 as described.

As also seen in FIGS. 2 and 3, the control means for the indexing meansincludes a switch which precludes the indexing operation unless a supplymagazine is properly positioned on the support base. Normally projectingfrom the upper surface of the support base is an arm of switch 53 whichis depressed into an accommodating slot in the support base when amagazine is properly positioned thereon. in the absence of such amagazine, switch 53 effects an override control on the servomotor andprecludes indexing movement of the support base in the manner describedpreviously. That is, such switch senses the presence or absence of afeed magazine and looks out automatic indexing of the support base whenno magazine is present.

Because the construction and control operations of the upper and lowerlimit switches and the magazine presence sensing switch areconventional, details of their mode of operation and construction havenot been included herefrom.

WAFER OUT-FEED AND TRANSFER MEANS Withdrawing of successive wafers fromthe supply magazine is effected by the wafer withdrawal or out-feed andtransfer means 2. As seen in FIGS. 2 through 8, such transfer means inthe illustrated embodiment includes improved fluid-bearing mechanismdefined by an air-bearing track structure posi' tioned closely adjacentto and at least partially underlying the supply magazine body 11. Asbest seen in FIGS. 2 through 4, such bearing track structure includes agenerally T-shaped metal or plastic retainer plate 56supported at itslaterally opposite ends as seen in FIG. 2 by the aforementioned spacedupstanding mounting plates 49, above the main base plate 31 of theapparatus. Suitable screw fasteners 57 maintain the retainer plateengaged with the upstanding plates 49.

As shown in FIGS. 4 through 6, a series of parallel open slots 58, threein number in the embodiment illustrated, are formed in the upper surfaceof the retainer plate and extend longitudinally of the apparatus for thefull length of the retainer plate. Slots 58 are generally rectangular invertical cross section having generally planar parallel sidewalls 59(FIG. 6). A plenum chamber 61 extends transversely of the retainer plateas also seen in FIG. 6, and a series of spaced openings 62 extendupwardly through the retainer plate and connect the plenum chamber withthe slots 58.

A metal or plastic closure plate 63 is secured in any suitable fashion,such as by bolts 64 (FIG. 6) to the undersurface of the retainer plateto seal off the plenum chamber. Gasket means (not shown) may be employedto insure an airtight seal. Passing through closure plate 63 is a borein which a fitting 66 is threadedly engaged. Fitting 66 is connected bymeans of a hose 67 or like connection with a source of supply of thewafer supporting fluid be introduced into the plenum chamber through thefitting. Such source of supply in the preferred embodiment comprises aquantity of pressurized air provided by a compressor (not shown) inknown fashion.

It will be noted from FIGS. 4 and 5 that the aforementioned sensor 46projects through retainer plate 56 and closure plate 63 and is supportedthereby in the operative position noted previously.

The fluid-bearing track structure illustrated is completed by a seriesof parallel nozzle bars 68 each of which is positioned in andsubstantially fills an associated slot 58 in the retainer plate. It willbe noted from FIGS. 2 and 4 that the bars are contoured to conformclosely to the transverse dimension of the respective slots 58 and areof a length to substantially fill such slots. It will also be noted thatthe center bar is substantially longer than the side bars because of theincreased length imparted to the center slot by the T-shapedconfiguration of the retainer plate. The center bar defines that portionof the fluid hearing which projects into the supply magazine body 11 andeffects withdrawal of wafers therefrom in the sequential manner referredto earlier. That is, the center bar 68 underlies each successive waferindexed in the withdrawing position so that air introduced through thecenter bar may lift the wafer from its supporting lip in the supplymagazine and transfer the same from the magazine for subsequentprocessing.

To effect such wafer withdrawal, the air introduced through the retainerplate by the nozzle bars is directional in nature and such direction isimparted thereto by the improved and novel configuration of the airpassages provided by the nozzle bars as seen in FIGS. 5 through 8.

As best seen in FIGS. 7 and 8, each of the bars 68 is provided with agenerally T-shaped configuration having generally parallel side faces 69which are cutaway along the bottom of the bar to provide elongatedchannels 71 extending longitudinally of the bar. Such channelscommunicate with the openings 62 passing through the retainer plate 56from the plenum chamber 61 so that air from the plenum chamber may passthe full length of the bars. Such channels 7i terminate inlOl025 0050wardly of the opposite ends of the bars, however, to seal off the endsof the slots 58 in which the bars are positioned. Note FIG. 6.

The nozzle bars are dimensioned to substantially fill the retainer plateslots 58 and upper edges of the bars lie substantially coplanar with theupper surface of the retainer plate to thereby provide a smooth bearingsurface over which the wafers may pass. To retain the bars in place, asseen in FIG. 4, a series of screws 72 pass upwardly through the retainerplate into the bars.

The opposite side faces 69 of the bars engage the smooth opposed sidefaces 59 of the respective retainer plate slots. To provide airpassages, the bar side facesare provided with means which define animproved air nozzle construction. Such air passages comprise a series ofspaced grooves 73 formed in the opposite side faces of the bars. Formost effective air bearing, each of the grooves is directionally formedto impart longitudinal motion to wafers supported thereby.

In that regard, such directional capability is produced by providingeach groove with a predetermined exit angle inclination relative to thelongitudinal axis of the bar. Further in that regard, each groove 73preferably is formed with a nozzle configuration provided by formingsuch groove wider and deeper at the end thereof which communicates withthe channel 71 and progressively tapering the groove so that it becomesnarrower and less deep at the exiting end thereof. note FIGS. 7 and 8.Such nozzle construction has been found highly effective in insuringpositive control and movement of wafers or other articles to betransported by fluid-bearing structure of the type disclosed.

As noted by the dotted lines 70 in FIG. 5, preferably each of the nozzlegrooves 73 is formed as a portion of the arc of a large circle, thecenter of which is spaced from the axis of the bar. The exiting angle ofair passing from the arcuate grooves may be varied to meet a particularneed in accordance with known considerations, such as the speed andextent of longitudinal movement desired for transporting articles. Suchinclina' tion also may be varied in accordance with the weight of thearticles to be handled as well as other factors known in thefluid-bearing art. By way of example, an exit angle within the range ofto 25 has been found effective for transporting many articles, of whichwafers are exemplary.

Except for their length, each of the bars 68 is substantially identicalin configuration in the embodiment illustrated although it should beunderstood that modifications and variations in the construction betweenthe respective bars may be effected if desired. For example, if it isdesired to impart positive wafer centering control to the air-bearingtrack structure to insure passage of successive wafers generally alongthe longitudinal axis of the track structure, the opposite side bars mayhave the nozzle grooves thereof formed to extend inwardly toward thelongitudinal axis of the track structure to impart an inward directionto the airflow emanating therefrom. Also, by varying the contour or sizeof the nozzle grooves in the side bars relative to the grooves in thecenter bar, thereby imparting a pressure differential to the airemanating from the side bars relative to the center bar, such centeringcontrol may also be obtained.

While in the embodiment illustrated it is contemplated that air willpass continuously through the bars when the bearing is operating totransport articles, by the inclusion of a suitable and known air pulsingmechanism (not shown) into the air supply line 67, air may beintermittently introduced through the air-bearing track structure tomove the wafers in successive up and down steps along the length of theair bearing. For certain articles being handled with an air bearing ofthe subject type, such air pulsing has been found desirable for moreeffective transfer of articles therealong.

Furthermore, while the air-bearing embodiment described has singledirectional capability, an alternative embodiment described hereinafteris contemplated also in which the airbearing structure is imparted withbidirectional capability so that articles may be alternately moved alongbe same bearing structure is opposite directions relative to a referencelocation, as may be required in a particular handling procedure.

In the illustrated embodiment, the air-bearing track structure describedtransports wafers in succession from the supply magazine to the adjacentcentering station at which a centering operation is performed on thewafers for the purpose to be described.

WAFER CENTERING MEANS Referring to FIGS. 2 through 5 and 9, means forreceiving and centering successive wafers fed thereto from a suitablesource of supply prior to their transfer to the treating station isillustrated. While a supply magazine is shown herein as such source, itshould be understood that wafers could originate from other supplysources, such as another processing machine or an infeed supply conveyorof any suitable type.

Such centering means comprises the aforementioned centering unitdesignated 3 which is defined by a generally flat metal or plastic dish76 which, as seen in'FlGS. 2 and.4, is generally square in outline whenviewed from above. The dish is formed with a shallow regular concaveupper surface 75 which deepens increasingly from the respective outeredges of the dish in regular contour toward the center thereof,designated 77 in FIG. 4. The dish is secured directly to and supportedby the retainer plate 56 of the air-bearing structure by means of capscrews 79 extending through the retainer plate into one edge 78 of thedish, as best seen in FIG. 4. Around its periphery on the otherthreeedges of the dish is a continuous lip, which projects above theupper concave surface of the dish and is provided by a series of flatmetal bands 81 secured to the dish edges by capscrews 82. The continuouslip formed by the metal bands forms a retainer which precludesinadvertent movement of wafers over an edge of the dish during acentering operation. From FIGS. 2, 4 and 5, it should be obvious thatwafers are introduced directly by the air-bearing structure onto theupper concave surface of the centering dish for handling therein.

Wafer centering in dish 76 is effected by fluid passing upwardly throughthe dish to engage individual wafers positioned in sequence on the uppersurface 75 thereof. Wafer supporting fluid, preferably of the pneumatictype, is passed through series of air passages provided through thedish. In the embodiment illustrated in which the dish is cast ormachined from a metal or plastic plate, such air passages comprise aseries of regularly spaced holes 83 provided along radii emanating fromthe center 77 of the dish and arranged in concentric circles locatedthereabout. However, it should be understood that alternativeconstructions are contemplated, such as by forming the dish from aporous metal, such as powdered bronze, which because of its inherentporous structure includes myriad air passages therethrough. The dishconstruction illustrated, however, is preferred for the handling ofwafers as disclosed herein.

A plenum chamber 84 is provided beneath the dish and is formed by aclosure plate 86 secured by capscrews 87 (FIG. 5) to the undersurface ofa peripheral flange 88 of the dish. The closure plate 86 interfits withflange 38 and a shoulder 89 of the plate is engaged beneath the flangeas shown in FIG. 5. To prevent air leakage from the plenum, an O-ringseal 91 is interposed in a groove provided between the flange 83 andshoulder 89.

Extending through he closure plate and communicating with the plenumchamber 84 is a fitting 92 connected by a hose 93 to an air supplysource, such as a conventional air compressor (not shown). Airintroduced through hose 93 and fitting 92 passes into the plenum chamberand through the spaced openings 83 upwardly through the dish to emanatetherefrom into contact with a wafer positioned on the concave surface75.

By utilizing a conventional air pulsing unit (not shown), air introducedonto the upper surface of the dish may be caused to exit in rapidpulsations so that a wafer engaged thereby is lifted and droppedrepeatedly and rapidly, yet without damage thereto. Such reciprocationof the wafers by pulsing air currents moves the wafer from adjacent theperiphery of the dish to the center thereof. The air pulsations arecontinued for a predetermined time sufficient to move the wafer untilits center overlies the center 77 of the dish. Once the wafer ispositioned over the dish center, continued air pulsations will notdisrupt the centered orientation. When the pulsations are stopped, thewafer settles onto the dish with its center concentric with the dishcenter 77.

While the frequency of the pulsation cycles will vary with the type andsize of articles being centered, for silicon wafers a pulsing frequencyin the range of l to cycles per second has been found effective, with 2to 4 cycles being generally suitable. As noted previously, the centeringmechanism can accommodate articles of widely varying sizes.

Mechanism also is provided to elevate each properly centered wafer abovethe dish to permit the same to be engaged by the aforementioned pickupand transfer means to be described in detail hereinafter. Such elevatingmechanism comprises a hollow pin 96 (FIGS. 4, 5 and 9) which extendsthrough a bore 97 formed concentric with the center 77 of the dish. Theaxis of pin 96 is similarly concentric with the dish center. It will benoted from FIGS. 5 and 9 that the dish is formed with a dependingcylindrical extension 98 through which pin 96 passes. Extension 98 inturn is snugly received within a depending cylindrical extension 99 ofthe aforementioned closure plate 86 and an O-ring seal 100 is positionedin a suitable groove 101 and is interposed between the respectiveextensions to preclude air passage therebetween.

The bore 102 of the hollow centering pin 96 is connected at its lowerend to a vacuum source, designated generally by the fitting 103 in FIG.9. As the pin is moved upwardly from the lower position in FIG. 5 to theelevated position shown in dotted lines in that figure and in solidlines in FIG. 9, vacuum is automatically applied through bore 102against the undersurface of a wafer positioned above the pin, therebymaintaining the wafer securely engaged with the upper end of the pinwith its center essentially coincident with the axis of the pin.Movement of the pin 96 upwardly, and subsequent movement of the pindownwardly, is effected by a conventional air cylinder, generallydesignated 104 in FIG. 9. Pin 96 is connected within the cylinder to aslidable piston contained therein. In known fashion, upon introductionof air against the underside of the piston in the cylinder, the pin willbe elevated and upon exhausting of air from the underside of the pistonand introduction of air into the cylinder above the piston, the pin willbe retracted. The piston control sequence in that regard, coupled withthe introduction and removal of vacuum from the pin bore, is effectedautomatically by control means in the manner to be describedhereinafter.

It should be understood that fluid is shutoff to the out-feed fluidbearing 2 while centering of a wafer is being effected to precludeinterference with such centering by another wafer.

Centered wafers are transferred in succession from the centering unit bypickup and transfer means to the treating station adjacent the centeringstation. The transfer means for moving wafers from the centering unit tothe treating station is operatively interconnected with other transfermeans for moving treated wafers from the treating station toward thedischarge station. Prior to describing the respective first and secondinterconnected pickup and transfer means, and their actuatingmechanisms, details of the components of the wafer treating unit locatedat the treating station will first be described.

WAFER SPINNING AND COATING MEANS Properly centered wafers aretransferred in succession into and received by the treating unitdesignated 6. In the embodiment illustrated herein in which siliconwafers intended for the manufacture of electronic components are beingtreated, the treating unit disclosed is designed to apply a measuredamount of fluid material, such as a liquid photoresist material commonlyemployed in the electronics industry, to each wafer positioned at thetreating station and to distribute such material evenly across the uppersurface of each such wafer. Such photoresist material, by way ofexample, may be Eastman Kodak Companys KPR," KMER" or KTFR," commonlyused in the trade.

Details of the treating unit for spinning and coating wafers are shownin FIGS. 2, 3 and 11. Projecting upwardly from and secured to-main baseplate 31 in any suitable manner, such as by welding, is a dispensingmechanism support plate, designated 111 in FIGS. 2 and 3, from the topof which pro jects in generally parallel relationship to the main baseplate 31 a mounting plate 112 which is secured by a series of bolts 113to the upright support plate 111. As seen in FIG. 11, a fluid dispenserhead assembly, generally designated 114, is supported above plate 112 byan intermediate hollow mounting housing 116 secured by dowels 117 toplate 112. Other dowels 1 18 in turn secure the head 114 to the housing116.

Housing 116 is provided with a central bore 119 in which a dispensingnozzle 121 is located. Dispensing nozzle 121 in turn is connected bysuitable valve structure 122 with a supply hose 123 which in turn isconnected with a pressurized supply container 124 (FIG. 2) of knownconstruction in which a quantity of photoresist material is maintainedunder pressure for dispensing in predetermined measured amounts inresponse to opening of the valve structure 122 which regulates thenozzle 121. Nitrogen is commonly used as the pressureproducing medium incontainer 124. The dispensing head and supply structure employed areconventional and further details thereof will not be presented herein.

As best seen in FIG. 11, located directly beneath the dispensing nozzle121 is a rotatable spindle 126 on the upper end of which successivewafers are to be placed by the pickup and transfer means to bedescribed. Such wafers are located on the spindle with their centersessentially coincident with the vertical axis of the spindle 126. Itwill be noted that spindle 126 is provided with a hollow bore 127running the length thereof which in turn is in operative communicationby means of a fitting 128 and supply hose 129 with a vacuum source. Uponthe application of vacuum to the spindle, wafers placed on the upper endof the spindle are firmly held in place thereon during high speedrotation of the spindle for the purpose to be described.

Rotation of the spindle may be effected in any suitable manner, such asby a small electric servomotor, generally designated 131, the operationof which is effected in sequence as wafers are properly oriented on thespindle upper end. It should be understood that photoresist fluiddispensing and spindle rotation are effected in timed relationship witheach other so that photoresist material placed on each successive waferwill, upon rotation of the spindle, be spread by centrifugal forceequally across the face of the wafer to effect uniform coating thereof.

If desired, several photoresist material layers may be applied to thesame wafer depending upon the subsequent utilization intended fro thewafer in later manufacturing steps. Also, each wafer may be rotated bymotor 131 in two stages if desired, the first of which is a slow speedrotation to effect spreading of the photoresist material, and the secondof which is a high speed rotation to insure even distribution of thephotoresist material.

The spinning and coating unit of this invention includes improvedfeatures comprising mechanism provided to maintain the unit free ofsolidified photoresist fibers which may be thrown from the wafers duringspinning thereof. Such mechanism is in the form of an extensible andretractable cup structure, generally designated 132 in FIG. 11, which iscooperable with the aforementioned housing 116. The cup structurecomprises a generally cylindrical cup 133 open at its top and having acentral opening 134 in its base 135 which allows the cup to surround andmove longitudinally of spindle 126. The inner wall of the cup is taperedinwardly towards its open top and extends a substantiai distanceupwardly from its base 135 to catch any photoresist material fiberswhich are thrown outwardly by centrifugal force during wafer coatingoperations. As noted in FIG. 11, structure is provided to selectivelyelevate the cup from the solid line'retracted position shown to thedotted line extended position shown.

It will be noted from the dotted line showing of FIG. 11 that, when cup133 is in the elevated position, its wall surrounds and substantiallyencloses the lower portion of the housing 116 which as'seen is providedwith a downwardly extending peripheral flange 136. Thus, the wall of thecup 133 and the flange 136 cooperate to define a substantially enclosedchamber surrounding the wafer when the cup is in the elevated positionwhich eliminates the possibility of photoresist material fouling upadjacent components of the apparatus.

It will also be seen from FIG. 11 that exhaust structure is provided toremove solidified or unsolidified photoresist material from the cupduring a coating operation, such structure comprising a vacuum exhausttube 138 secured to the base of the cup 135 and a support plate 137therefor and extending therethrough. The exhaust tube is connected to anexhaust hose 139 which in turn is connected with a source of vacuum anda'waste disposal outlet (not shown).

The structure provided for elevating and retracting cup 133 isdesignated 141 in FIG. 11. In the preferred embodiment, the supportplate 137 to which the base of the cup is secured is provided with alateral extension 142 to which is secured a connector 143 which forms aseat for a piston rod 144 engaged therewith. Rod 144 in turn extendsinto an air cylinder I46 and is connected within the cylinder to apiston (not shown) by means of which the support plate 137 and the cupcarried thereby may be selectively elevated or retracted in accordancewith the introduction of air against one side or the other of the pistonin known fashion. The timing sequence for piston operation to extend orretract the cup in conjunction with the sequence of operation of othercomponents of the apparatus will be described hereinafter.

As seen in FIG. 3, cylinder 146 is secured by a bracket 147 to the mainframework of the apparatus in any suitable fashion. A guide bearing 148is mounted atop the bracket 147 and a slidable guide rod 149 is movablethrough the hearing. The of the guide rod is secured by a connector 150to the lower end of aforementioned piston rod 144. The connector atopposite upper and lower ends of the stroke of piston rod 144 contactsdepressible upper and lower limit switches 140 and 145 respectively forthe control purpose described hereinafter.

Following photoresist coating or other similar treatment of individualwafers in sequence at the treating station, they are transferred fromthe treating station towards the discharge station by pickup andtransfer means provided for such purpose.

WAFER PICKUP AND TRANSFER MEANS In the apparatus embodiment illustratedthe aforementioned first and second means 4 and 7 are provided forpicking up and transferring wafers from one station to another. Suchmeans are utilized to move wafers in timed sequence, first, from thecentering station to the treating station, and second, from the treatingstation toward the discharge station.

In the apparatus embodiment illustrated, the respective pickup andtransfer means employed are operatively interconnected with each otherto effect simultaneously movement of one wafer from the centeringstation to the treating station while another wafer is being moved fromthe treating station towards the discharge station. However, it shouldbe understood that operatively discreet but intertimed pickup andtransfer means could be employed if preferred, rather than the directlyinterconnected first and second transfer means illustratedherein.

The construction of the pickup and transfer means and the relationshipthereof to the other components of the apparatus is illustrated in FIGS.2, 3 and 9 through 16. In general terms the pickup and transfer meanscomprises a pneumatic cylinder actuated slide structure on which waferpickup structures, preferably in the form of vacuum arms, are carried.Upon actuation of the cylinder, the slide structure is moved betweenpredetermined positions in which the respective pickup arms are engagedwith wafers supported on the centering pin 96 and spinning spindle 126at the centering-treating stations respectively.

Reference is directed to FIGS. 12 and 13 for a detailed showing of thepreferred embodiment of the slide structure which comprises a generallyU-shaped flat slide plate 151 having an elongated slot 152 which extendssubstantially the full length thereinto from one end thereof. The slideplate is positioned to extend below the centering and treating stationsand slot 152 permits movement of the plate relative to spinning spindle126, vacuum exhaust tube 138 and cup elevating piston rod 144, as wellas the centering pin air cylinder 104, as seen in FIG. 12.

The slide plate is mounted fro longitudinal movement of the apparatusrelative to the stations mentioned by means of three slide bearings 153,154, and 156 respectively secured by suitable screw fasteners 157 to theunder surface of the plate. The bearings in turn are slidably positionedaround two cylindrical guide tracks 159 and 161 which extend in parallelrelationship beneath the slide plate. The guide tracks are supportedbetweenopposite end mounting brackets 162 and 163 which project upwardlyfrom an inverted U-shaped mounting channel 164. Mounting channel 164provides the main base or support for the slide structure and it in turnis supported in any suitable fashion, such as by bolting or welding, toan upright frame member 166 connected with the main base plate 31 of theapparatus as best seen in FIG. 3. It should be understood that themounting channel has suitable apertures provided therethrough at spacedlocations therealongto accommodate those upwardly projecting componentsof the apparatus previously described which are positioned at thecentering and treating stations.

Referring again to FIGS. 12 and 13, it will be noted that guide track159 is provided adjacent its opposite ends with enlarged portions 167which define stop shoulders 168 which are engageable by the bearings torestrict movement of the slide plate within positive limits. To effectmovement of the slide plate, air cylinder structure 171 is providedwhich is supported by a laterally extending upright brace 172 from theapparatus framework in any suitable fashion. Cylinder 171 is secured atone end to the brace 172 by a bolted connector 173. Projecting from theother end of the cylinder is a piston rod 174 having an L-shapedconnector 176 bolted to its outer end. Such connector in turn is securedby bolts 177 to an adjacent edge of the slide plate 151. Thus, uponintroduction of air against one surfaceor the other of the piston in thecylinder which is connected with the piston rod 174 in known fashion,the slide plate may be moved selectively towards the right or left inFIGS. 12 and 13.

Projecting upwardly from opposite corners of the slide plate are wafertransfer arms 181 and 182. Each of the transfer arms is designed tosupport a wafer on its upper surface and to maintain the water engagedtherewith by the application of vacuum thereto. To permit properpositioning of the wafers during engagement and disengagement thereofwith the respective vacuum arms, the vacuum arms are mounted forselective vertical movement within well defined limits.

Each of the vacuum arms is similarly mounted on the slide plate for suchvertical movement and reference will be directed to the showing of FIGS.12 and 13 with respect to the mounting structure for vacuum arm 182only, it being understood that the mounting arrangement for vacuum am181 is identical in construction therewith, only reversely orientedbecause of the reverse orientation of am 181 relative to arm 182.

A notch 183 is provided in the side edge of slide plate 151 generallycentrally of its opposite end edges as best seen in FIG. 12. In suchnotch is positioned a generally rectangular mountingblock 184 which issecured to the slide plate by screw fasteners 186. The mounting blockdepends below the undersurface of the slide plate and a pivot pin 187 ispositioned to extend laterally outwardly therefrom. Pivot pin 187 inturn carries thereon a pivotal lever arm 188 on one end 189 of whichvacuum pickup arm 182 is secured by means of screw fasteners 191. Thus,it should be understood that up and down movement of the pickup armwithin predetermined limits is permitted as lever arm 188 pivots aboutthe axis of pin 187.

Lever arm 188 is urged in a counterclockwise direction (FIG. 13) by acompression coil spring 192 interposed in bores provided in the slideplate and the end of the lever arm which is opposite from the pickup arm182. Spring 192 thus tends to urge the pickup arm towards its raisedposition. Limits are placed on the amounts of clockwise orcounterclockwise movement by means of a pair of adjustable setscrews 193and 194 depending from the slide plate into engagement with the uppersurface of the lever arm. Thus, the extended and retracted positions ofthe pickup arm carried by the leverarm may be adjusted withinpredetermined desired limits.

It will be noted from FIG. 12 that lever arm 188 is provided with anelongated slot 196 which accommodate therein the mounting block 184.Slot 196 permits pivotal movement of the lever arm for the purposedescribed.

As best seen in FIGS. 9 and 15, the pickup arms 181 and 182 aresubstantially identical in construction with minor distinctions thereinbeing prompted by the relationship of the respective arms to thestations to and from which wafers are transferred thereby. In FIGS. 9and 15 corresponding numerals are used to identify correspondingcomponents of the respective arms. Each pickup arm includes an uprightgenerally flat body portion 196 having a vacuum channel 197 passingtherethrough. A horizontal generally flat upper body portion 198,through which an extension of channel 197 projects, is integrallyconnected with the upright body portion and such horizontal portionterminates in an upwardly extending head portion 199. It will be notedthat the head portion of arm 181 is longer than the corresponding headportion of the arm 182 because of the interrelationship of arm 182 withthe fluid-bearing track structure 8 (FIG. 15) when a wafer is dischargedonto the track structure.

As seen in FIGS. 10 and 16, the vacuum channel 197 in each of the vacuumarms terminates in an enlarged transversely extending chamber 200, suchchamber being closed by a flathead plate 201 secured by screw fasteners202 to the upper surface of the head portion 199 of the respectivetransfer arms. A series of spaced openings 203 extend through therespective headplates to permit vacuum atmosphere to be introducedagainst the undersurface of a wafer engaged by a pickup arm in themanner illustrated in FIGS. 9 and 15.

FIGS. 9 and 15 also show vacuum fittings 204 which are connected withthe respective lever arms 188 from which the pickup arms project. Suchfittings communicate with bores 205 provided in the lever arms inalignment with the vacuum channels 197 formed in the pickup arms. Therespective fittings are connected by hoses 206 with a suitable vacuumsupply.

It should be understood that vacuum is introduced selectively into theindividual pickup arms as each is brought into engagement with theundersurface of a wafer and that such arm is selectively elevated andretracted about the pivot axis of its associated lever arm 188 inconjunction with engagement and transfer of such wafer. The sequence ofoperation and control means employed for selectively elevating andretracting the pickup rms and for actuating the slide plate on which thearms are carried is described hereinafter.

As noted previously, the coil spring 192 tends to urge its associatedlever arm counterclockwise (FIG. 13) which in turn urges the pickup armmounted thereon toward its upper extended position. However, to permitproper positioning of the respective headplates 200 of the pickup armsrelative to wafers to be picked up or released therefrom, structure fordrawing the respective vacuum arms downwardly and holding them in thelower retracted position is provided. In the illustrated embodiment,such structure takes the form of duplicate air cylinders 207 (FIG. 13)each of which is connected by a hose 208 with a suitable air pressuresource. Within each cylinder 207 is provided a single action pistonwhich is operatively engaged with a lever arm 188. That is, the pistonis mounted on and secured to the lever arm in any suitable fashion and apiston rod 209 projects from the upper end thereof and is engaged withtheundersurface of slide plate 151. Upon introduction of air against theunder surface of the piston, piston rod 209 is urged upwardly againstthe slide plate to force the piston downwardly and to rotate the leverarm clockwise against the urging of spring 192 to lower the pickup arm.Thus, so long as air is introduced against the piston in cylinder 207,the pickup arm carried by the lever arm will be held retracted.

Such retracted positioning of the pickup arms is maintained during themajor portion of the cycle of movement of the slide plate 151 describedpreviously. Periodically, however, air is exhausted from the respectivecylinders 207 to pennit the springs 192 to elevate the pickup arms inthe timed sequence necessary to effect wafer transfer between thecentering, treating and discharge stations.

The sequence of up and down movement of pickup arm 182 is as follows. Asthe pickup arm is moved from the rest position of slide plate 151, thearm is held retracted. When the pickup arm is aligned by the slide platewith the centering pin 96 at the centering station, the arm is elevatedin conjunction with simultaneous retraction of the centering pin andwithdrawal of vacuum from the pin and introduction of vacuum into thearm to effect wafer pickup. Slide plate 151 then moves the pickup armtoward the treating station and the arm is retracted when it is alignedwith spinning spindle 126. Vacuum is then withdrawn from the arm andvacuum is introduced into the spindle to effect transfer of a wafer tothe spindle. The pickup arm is held retracted until it is again alignedat the centering pin at the centering station.

The sequence of up and down movement of pickup arm 181 is as follows. Aspickup arm 182 is moved to the centering station, pickup arm 181 ismoved to the treating station and is held retracted during suchmovement. When pickup arm 181 is aligned with spinning spindle 126, thearm is elevated and vacuum is introduced thereinto as vacuum iswithdrawn from the spindle to effect wafer pickup by the arm. Slideplate 151 then moves the pickup arm toward the discharge station andwhen the arm is properly positioned with respect to the wafer infeed andtransfer fluid-bearing track structure 8, the arm is retracted as vacuumthereto is withdrawn therefrom to deposit the wafer on the trackstructure for introduction thereby into the discharge magazine. Thepickup arm is held retracted until it is again aligned with the spinningspindle at the treating station.

WAFER INFEED AND TRANSFER MEANS Introduction of successive coated wafersinto the discharge magazine is effected by the wafer infeed and transfermeans designated 8 and best seen in FIGS. 2, 3, 14 and 15. In thisconnection, the wafer infeed and transfer means of the illustratedembodiment comprises a fluid-bearing track structure which preferably isin all essential respects substantially identical to the out-feed andtransfer means described previously in conjunction with the supplymagazine. Therefore, a detailed description of the infeed fluid-bearingtrack structure which is interposed between the treating station andthedischarge magazine will not be set out in detail. However, correspondingreference numerals, primed, are used in the drawings to designate thosecomponents of the infeed fluid-bearing track structure which correspondto the counterpart components of the previously described out-feedfluid-bearing track structure.

However, the infeed track structure includes one important modificationnot incorporated into the previously described out-feed track structure.Such modification is most evident from FIGS. 2, 14 and and comprises theprovision of a vacuum pickup arm accommodating slot 212 which extendsfrom an edge thereof into retainer plate 56' so that pickup arm 181 mayposition a coated wafer directly over the track structure prior toretraction of the arm as previously described. Thus, a wafer may bedeposited directly on the upper surface of the track structure fortransfer thereby directly into the adjacent discharge magazine 11'.

Note should also be given to the fact that the infeed fluidbearingstructure includes in conjunction therewith a fibreoptic sensor 46 ofthe type described previously which regulates airflow to the trackstructure during indexing of the discharge magazine in the same mannerdescribed previously with respect to sensor 46. 1

WAFER DISCHARGE MAGAZINE STRUCTURE AND INDEXING MEANS Reference isdirected to FIGS. 1 through 3 for an illustration of the components ofthe apparatus employed at the wafer discharge station 9. As mentionedpreviously, at such station is provided a wafer discharge magazine 11 inwhich are receivable a plurality of wafers, the number of whichcorresponds to the number of wafers withdrawn from the .supply magazine1 1 provided at the feed station 1.

The discharge magazine and the indexing means therefore are in allessential respects identical to the feed magazine 11 and the indexingmeans therefor as described herein previously. Therefore, a detaileddescription of the discharge magazine and its indexing means will not beset out. Those components of the apparatus employed at the dischargestation which correspond to counterpart components at the feed stationare identified by corresponding reference numerals, primed, in thedrawings.

However, the indexing means at the discharge station differs from thatprovided at the feed station in several respects in that the directionof discharge magazine indexing is opposite from that at the feedstation. Servo motor 38' at the discharge station is actuatable toeffect vertical movement of the discharge magazine 11' in an upwarddirection as the magazine becomes increasingly filled with wafers. Thatis, in the initial stages of operation, the discharge magazine ispositioned with its uppermost slot one step above the surface of theinfeed fluid-bearing track structure 8. Then, upon actuation of theindexing means, the uppermost slot and then the underlying slots arebrought sequentially into alignment with the track structure as themagazine is moved upwardly with the support base 16' indexed by theservomotor 38.

Such upward indexing may be effected by employing a servomotor whichrotates its associated threaded drive rod 36' in a direction oppositefrom that in which the drive rod 36 at outfeed station rotates or,alternatively, drive rod 36' may be provided with threads of an oppositehand from those on drive rod 36. In any event, indexing of the supplymagazine and the discharge magazine preferably is effected in oppositevertical directions for most effective wafer handling.

APPARATUS CONTROL AND OPERATION SYNCHRONIZING MEANS The variousoperations of the respective apparatus components and units previouslydescribed are regulated by a series of solenoid controlled air andvacuum valves which in turn are actuated through a series of switches inpredetermined sequence to effect transfer and treatment of a series ofwafers in the apparatus without interferring with each other. Thecircuitry for such control switches has not been illustrated ordescribed in that such circuitry is conventional and within the skill ofthose knowledgeable in the electrical control art.

Reference is directed to FIG. 20 for a generally schematic showing ofthe respective air valves and pistons actuated thereby, as well as therespective vacuum valves employed. From a study of such figure, theoperation of the respective valves, and the control functions performedthe reby, should become evident when taken in conjunction with thedisclosure of the apparatus components regulated thereby presentedpreviously herein.

Operation and control of the supply magazine and discharge magazineindexing means has already been described. The sequence of operation andcontrol of the vacuum pickup arms 181 and 182 with respect to theoperations and control of the centering pin 96 and the spinning spindle126 are the important control functions remaining to be described.

As noted previously, the respective pickup arms 181 and 182 are movablesequentially upwardly and downwardly in response to actuation of thelever arms 188 on which they are mounted by their associated aircylinders 207 and coil springs 192. As also has been mentioned, eachwafer is held on the centering pin and the spinning spindle, and on thepickup arms during wafer transfer, by a vacuum atmosphere. If a waferspinning and coating cycle is taking place at the coating station, awafer is held on the centering pin until the spinning cycle has beencompleted. During such waiting interval, the respective pickup arms aregenerally midway between the ends of their wafer transfer paths so thatthe arms do not interfere with the cup 133 which catches excessphotoresist material when the cup is elevated. That is, referring toFIG. 13, the respective pickup arms are held in the intermediate rest"position shown in dotted lines in FIG. 13.

Upon completion of the spinning cycle, slide plate 151 is moved towardsthe right in FIG. 13 to the end of its path by air cylinder 171 to movepickup arm 182 into alignment with centering pin 96 and tosimultaneously move pickup arrn 181 into alignment with spinning spindle126. Following wafer pickup by the arms, the slide plate is movedtowards the left in FIG. 13 to the other end of its path to presentpickup arm 182 to the spinning spindle and pickup arm 181 to the infeedbearing track structure. Upward and downward movement of the respectivearms is effected as described previously. As seen in FIG. 20, air andvacuum valves are provided to effect the various operations of thetransfer arms and the slide plate to insure effective wafer transfer.The described sequence is repeated in succession until all wafers fromthe supply magazine have been treated and transferred into the dischargemagazine, at which time the apparatus is automatically shut off untilsubsequent supply and discharge magazines are properly positioned.

Reference is directed to FIGS. 12 and 13, taken in conjunction with FIG.20, for an illustration of the control switches which are activated toinitiate certain pickup arm and slide plate movements and functionsdescribed. In the subject embodiment, four such control switches areillustrated, identified by reference numerals 216, 217, 218 and 219,respectively, and are mounted on the aforementioned mounting channel164. It will be noted that switch 217 is mounted externally of channel164 while the remaining switches are mounted internally thereof. Also,switch 217 is fixedly mounted on the channel while the remainingswitches preferably are adjustably mounted by means of adjustment slots221 and 222 formed through the sidewall of the channel.

The respective switches have toggle arm actuators 223,224, 225, and 226,respectively, operatively engaged therewith in known fashion. Upondepression of the respective toggle arms, the msociated switchestransmit control signals in known fashion to the respective solenoidactivated air or vacuum valvesshown in FIG. 20. Mounted on the outeredge of slide plate 151 is a switch actuator plate 227 aligned with thetoggle arm 224 of switch 217 as best seen FIG. 12. Upon movement of theslide plate towards the left in FIG. 12, plate 227 will contact anddepress toggle arm 224 to actuate switch 217. The remaining switches216, 218 and 219 have their respective toggle arms aligned with theaforementioned slide bearings 154 and 156. As seen in FIG. 13, bearing156 is positioned for engagement with the toggle arms 225 and 226 oflOlOZS 0055 switches 218 and 219. Bearing 154 is positioned forengagement with the toggle arm 223 of switch 216.

Switch 219, when toggle arm 226 thereof is depressed by bearing 156 asseen in FIG. 13, transmits a signal to the solenoid valve which controlsair cylinder 171 which actuates the slide plate 151. The slide plate ishalted so that pickup anns 181 and 182 are located in the positionsshown in FIGS. 12 and 13 in which such arms are accurately aligned withthe respective axes of the centering pin and the spinning spindle.Switch 216, when its toggle arm 223 is depressed by bearing 154,transmits a signal to the solenoid valve which controls air cylinder 171to effect accurate positioning of the pickup arms 181 and 182 over thedischarge air-bearing track structure and the axis of the spinningspindle respectively. Thus, the two switches 216 and 219 control the endlimits of the path of travel of the slide plate and the transfer armscarried thereby and limit longitudinal movement of the slide plate whensuch switches are activated as described.

Referring to FIG. 13, when the slide plate is in its extreme left-handposition, switch actuator plate 227 will be positioned to depress thetoggle arm 224 of switch 217. When switch 217 is thus actuated, a signalis transmitted to the solenoid valves which regulate the respectivecylinders 207 which control the up and down movement of the respectivepickup arms. As such signal is transmitted, air is introduced into. thecylinders and the pickup arms are moved downwardly in the mannerpreviously described.

Movement of the slide plate toward the right from its extreme left handposition in FIG. 13 will bring bearing 156 into contact with toggle arm225 of switch 218 which transmits a signal to deactivate air cylinder171 and bring the slide plate to a halt with the pickup arms located inthe intermediate rest position so that cup 133 may be raised during aspinning operation. The slide plate remains in the rest position untilcup 133 is retracted and a complete new cycle can be initiated.Initiation of a new cycle is effected by the centering pin 96 asfollows.

The centering pin is elevated, following a suitable established timedelay to permit completion of wafer centering, by a signal transmittedas sensor 46 is cleared by a wafer. Such signal activates the centeringpin piston 104 to raise the pin. As the pin reaches its top position, alimit switch (not shown) is activated which actuates slide platecylinder 171 to move the slide plate from its rest position to theextreme righthand position seen in FIG. 13, at which time switch 219 isac tivated to stop the slide plate, to raise the pickup arm 182 bydeactivating cylinder 207, to initiate retraction of the centering pin,and to introduce vacuum into the pickup arm, as it is withdrawn from thecentering pin.

When the centering pin is fully retracted, another limit switch (notshown) is activated which initiates movement of the slide plate towardthe left in FIG. 13, with pickup arm 182 extended. As arm 182 comes intoline with spinning spindle 126, slide plate cylinder 171 is deactivatedby bearing 154 contacting switch 216. Simultaneously, actuator plate 227activates switch 217 to retract pickup arm 182 and to introduce vacuuminto the spindle as vacuum is shut off from the pickup arm. Fullretracting of the pickup arm activates slide plate cylinder 171 and theslide plate is moved to and stopped at the rest position with the pickuparms retracted.

When the slide plate reaches the rest position, cylinder 146 isactivated to raise cup 133. As the cup reaches its upper limit, thelimit switch 140 is activated to initiate the photoresist dispensing andspinning cycle. The cylinder 146 is again activated to retract cup 133after a predetermined time delay sufficient to permit completion of thespinning cycle. As the cup is retracted, limit switch 145 is activatedto move the slide toward the right in FIG. 13 so that another cycle isinitiated.

As pickup arm 182 is moving as described, pickup arm 181 is beingsimilarly moved by the slide plate and periodically elevated andretracted at the treating station and adjacent the discharge station asdescribed previously.

As the valve and switch control features may vary in details known inthe control art, details thereof have not been incorporated herein.Accordingly, it should be understood that. so long as the disclosedair-vacuum-movement sequence is produced, the control features anddevicesemployed may be selected in accordance with available technology.

BIDIRECTIONAL FLUID BEARING TRACK STRUCTURE The fluid-bearing structuredescribed herein previously is readily adaptable for bidirectionalarticle movement in a manner heretofore unknown in the fluid-bearingart. In that connection, reference is directed to FIGS. l7, l8 and 19 inwhich an exemplary bidirectional fluid-bearing track structure isillustrated. In basic respects, the modified tract structure shown inthese figures corresponds to the track structure described previouslyand comprises a generally T-shaped retainer plate 251 having a series ofelongated generally rectangular open grooves 252 provided in the uppersurface thereof in which air bearing nozzle bars 253 are positioned andheld in place in the manner described previously. A closure plate 254 issecured to the undersurface of the retainer plate. Each of the nozzlebars is generally T-shaped in cross section to provide longitudinalchannels 256 along opposite sides therein to form air passageways alongthe length of the bars. Such passageways in turn communicate with plenumchambers formed in the under surface of the retainer plate.

An important distinction in the bidirectional track structure embodimentshown from that described previously resides in the fact that twoadjacent plenum chambers are provided in the retainer plate which areidentified in FIG. 17 by reference numerals 257 and 258 respectively.The respective plenum chambers in turn are connected by fittings 259 and261 respectively with a source of pressurized fluid, such as an aircompressor, not shown.

It will also be noted from FIG. 17 that the respective plenum chambersare operatively but separately connected with the channels 256 formed onopposite sides of the respective nozzle bars. That is, plenum 257 isconnected by means of a series of holes 262 with the left-hand channelof the nozzle bars (as viewed in FIGS. 17 and 18) while plenum 258 isconnected by a series of holes 263 with the right hand channel of therespective nozzle bars.

In that same regard, referring to FIG. 19, the right side faces of therespective nozzle bars are provided with directional grooves 266, eachof which preferably has the improved tapered and curved nozzleconfiguration described previously. It will be noted from FIG. 19 thatgrooves 266 on the right side faces of the bars are directedlongitudinally toward the right. On the opposite left-side faces of thebars, similar directional nozzle grooves 267 are formed. However, asalso seen in FIG. 19, the left side grooves 267 are oppositely directedfrom the grooves 266. That is, grooves 267 are directed longitudinallytoward the left.

From the foregoing, it should be understood that by the selectiveintroduction of air through the respective plenums 257 and 258, anarticle, such as a wafer, positioned on the bidirectional fluid-bearingtrack structure shown may be moved longitudinally of the track either tothe right or to the left, depending upon which plenum has fluid pressureintroduced thereinto.

Suitable valve control mechanism, not shown, is available to effectselective introduction of air or other suitable supporting fluid intoand through the respective plenums in predetermined sequences or cycles.The improved track structure thus described has the advantage of beingutilizable, for example, to withdraw individual articles from a station(such as a wafer magazine) and to move the same to a treating station.Following treatment at such station, the same track structure may beused to transfer the same article back to the same station (and toreintroduce the same into the magazine in the illustrative example) in afashion heretofore unknown with fluid bearing structures. Thus, thebidirectional track structure imparts specialized article handlingcapability to the subject invention in a manner requiring minimumalteration of the basic unidirectional track structure principallydisclosed.

Having thus made a full disclosure of preferred illustrative embodimentsof the invention incorporated in the subject apparatus and method, andthe various components and subcombinations which cooperate to definesuch apparatus, reference is directed to the appended claims for thescope of protection to be afforded thereto.

We claim:

1. In combination in an apparatus for handling and treating articles,such as silicon wafers, without manual handling,

A. a supply magazine having a quantity of said articles spacedlypositioned therein,

B. means for withdrawing articles from said supply magazine,

C. means for indexing said supply magazine sequentially to presentarticles therein to said withdrawing means for removal thereby insequence,

D. means at a station spaced from said supply magazine for acceptingarticles presented thereto in sequence,

E. transfer means for moving articles in sequence to and from saidstation prior to and following acceptance of said articles thereat,

F. a discharge magazine for receiving a quantity of saidarticles inspaced relationship therein following release thereof from said station,

G. means for receiving articles in sequence from said transfer means andfor introducing such articles in sequence into said discharge magazine,and

H. means for indexing said discharge magazine sequentially to permitintroduction of such articles thereinto in sequence,

1. said means for withdrawing articles from said supply magazine andsaid means for introducing articles into said discharge magazine eachcomprising,

1. a fluid-bearing track structure positioned in close proximity to therespective supply and discharge magazines associated therewith,

2. a source of article supporting fluid in communication with said trackstructure, and

3. control structure for regulating introduction of supporting fluidinto and through said track structure in accordance with sequentialindexing of said magazines by said indexing means associated with therespective magazines.

2. The apparatus of claim 1 in which each said supply magazine and saiddischarge magazine comprises,

1. a generally U-shaped body in horizontal cross section,

and

2. a series of lips spaced one above the other in said body which arespaced from each other by open slots defined by adj acent pairs of saidlips,

a. each said slot opening toward the respective means associatedtherewith for withdrawing articles from such body and for introducingarticles into such body.

3. The apparatus of claim 1 in which each of said means for indexingsaid supply magazine and said discharge magazine comprises,

1. a support base for such magazine,

2. guide structure for said support base,

3. a drive rod engaged with such support base which is actuatable inpredetermined sequential increments determined by the spacing betweenadjacent articles in such magazine, and

4. power source mechanism for sequentially actuating said rod to effectincremental movement of said rod and such support base therewith.

4. The apparatus of claim 3 in which the respective movable rods engagedwith the respective supply and discharge magazine support bases aremovable by their associated power source mechanisms in oppositedirections so that one of said magazines is indexed sequentiallyupwardly and the other of said magazines is indexed sequentiallydownwardly.

5. The apparatus of claim 1 in which each said transfer means comprisesl. a movable plate structure,

2. a vacuum pickup arm mounted on said plate structure for movementtherewith relative to said station,

3. vacuum structure for maintaining an article on said pickup arm whensaid arm is presented to such article, and

4. means for moving said plate structure and said armtherewith-sequentially toward and away from said station during pickingup and transfer of articles relative thereto.

6. The apparatus of claim 5 in which said transfer means furtherincludes 5. structure mounting said pickup arm for selective up and downmovement relative to said plate to facilitate pickup and discharge ofarticles by said arm, and

6. mechanism for actuating said mounting structure in predeterminedtimed sequence to elevate and retract said pickup arm during articlepick-up and discharge.

7. in combination in an apparatus for handling articles, such as siliconwafers,

A. a magazine for receiving a quantity of said articles therein instacked relationship,

1. said magazine having a series of spaced article receiving slotstherein, 7

B. a support base on which said magazine is positioned,

C. fluid-bearing means, a portion of which extends into said magazinewhen said magazine is supported on said base, positioned adjacent saidsupport base for moving articles relative to the interior of saidmagazine, and

D. means for indexing said magazine in sequence in response'to movementof individual articles relative to the interior of said magazine,

1. said indexing means sequentially aligning said magazine slots insequence with said portion of said fluid bearing means which extendsinto said magazine to permit movement of individual articles in sequenceby said fluid-bearing means relative to the respective slots of saidmagazine.

8. The apparatus of claim 7 in which said fluid-bearing means comprises,

1. a track structure which projects into said magazine positioned onsaid support base, including a. a series of directional fluid passagesextending through said track structure,

b. said passages being oriented relative to the interior of saidmagazine to impart the desired direction of movement to said articlesrelative to said magazine,

2. a source of supply of article supporting fluid in communication withsaid passages, and

3. control structure for regulating introduction of supporting fluidinto said passages in accordance with sequential indexing of saidmagazine by said indexing means.

9. The apparatus or" claim 8 in which said passages insaid trackstructure are directionally oriented to move articles inwardly into saidmagazine when fluid passes through said passages.

10. The apparatus of claim 8 in which said passages in said trackstructure are directionally oriented to move articles outwardly fromsaid magazine when fluid passes through said passages.

11. The apparatus of claim 8 in which said track structure furthercomprises c. at least two series of said directional fluid passages,

d. one of said series of passages being directionally oriented to movearticles in a first direction relative to said magazine,

e. the other of said series of passages being directionally oriented tomove articles in another direction relative to said magazine,

and in which said control structure for regulating introduction ofsupporting fluid into said passages comprises a. structure permittingintroduction of said supporting fluid selectively into a predeterminedone or the other of said series of passages.

1. In combination in an apparatus for handling and treating articles,such as silicon wafers, without manual handling, A. a supply magazinehaving a quantity of said articles spacedly positioned therein, B. meansfor withdrawing articles from said supply magazine, C. means forindexing said supply magazine sequentially to present articles thereinto said withdrawing means for removal thereby in sequence, D. means at astation spaced from said supply magazine for accepting articlespresented thereto in sequence, E. transfer means for moving articles insequence to and from said station prior to and following acceptance ofsaid articles thereat, F. a discharge magazine for receiving a quantityof said articles in spaced relationship therein following releasethereof from said station, G. means for receiving articles in sequencefrom said transfer means and for introducing such articles in sequenceinto said discharge magazine, and H. means for indexing said dischargemagazine sequentially to permit introduction of such articles thereintoin sequence, I. said means for withdrawing articles from said supplymagazine and said means for introducing articles into said dischargemagazine each comprising,
 1. a fluid-bearing track structure positionedin close proximity to the respective supply and discharge magazinesassociated therewith,
 2. a source of article supporting fluid incommunication with said track structure, and
 3. control structure forregulating introduction of supporting fluid into and through said trackstructure in accordance with sequential indexing of said magazines bysaid indexing means associated with the respective magazines.
 2. asource of article supporting fluid in communication with said trackstructure, and
 2. guide structure foR said support base,
 2. a vacuumpickup arm mounted on said plate structure for movement therewithrelative to said station,
 2. a source of supply of article supportingfluid in communication with said passages, and
 2. a chamber formed in alower surface of said retainer plate in communication with a source ofarticle supporting fluid,
 2. a series of lips spaced one above the otherin said body which are spaced from each other by open slots defined byadjacent pairs of said lips, a. each said slot opening toward saidfluid-bearing means associated with said magazine for moving saidarticles relative to the interior of said magazine body.
 2. each saidarticle causing said sensor to transmit an indexing control signal tosaid power source mechanism.
 2. The apparatus of claim 1 in which eachsaid supply magazine and said discharge magazine comprises,
 2. a seriesof lips spaced one above the other in said body which are spaced fromeach other by open slots defined by adjacent pairs of said lips, a. eachsaid slot opening toward the respective means associated therewith forwithdrawing articles from such body and for introducing articles intosuch body.
 2. a series of lips spaced one above the other in said bodywhich are spaced from each other by open slots defined by adjacent pairsof said lips, a. each said slot opening toward the respectivefluid-bearing means associated with the respective magazines forwithdrawing articles therefrom and for introducing articles thereinto.2. guide structure for each said support base,
 2. each of said barshaving a. a series of spaced grooves formed in a side face thereof whichopen onto the upper surface of said retainer plate, b. said groovesbeing formed to open onto said upper surface at a predetermined angularinclination relative to the longitudinal axis of such bar.
 2. each sucharticle causing said sensor to transmit an indexing control signal toits associated power source mechanism.
 2. a second series of directionalfluid passages extending through said track structure each beinggenerally arcuately curved in configuration from a lower end thereoftoward the upper end thereof,
 3. the passages of said second seriesopening onto said track structure upper surface in a direction which isgenerally opposite from the direction in which the passages of saidfirst mentioned series open onto such surface,
 2. a series of lipsspaced one above the other in said body which are spaced from each otherby open slots defined by adjacent pairs of said lips, each said slotopening toward said fluid-bearing means positioned adjacent saidmagazine for moving said articles in sequence relative to the interiorof said magazine body.
 2. a plurality of fluid passages extendingthrough said dish surrounding the center thereof operatively connectedwith a source of supply of a supporting fluid, and
 3. mechanism forpulsing supporting fluid from said source through said passages toeffect generally reciprocating movement of an article on said surfaceuntil such article is positioned with its center overlying the center ofsaid dish, B. transfer means, for picking up and moving articles insequence fRom said centering means and for presenting such articles to astation spaced from said centering means while retaining the centeredorientation thereof, and for subsequently moving articles in sequencefrom said station.
 3. a drive rod engaged with each said support basewhich is actuatable in predetermined sequential increments determined bythe spacing between adjacent articles in such magazine, and
 3. Theapparatus of claim 1 in which each of said means for indexing saidsupply magazine and said discharge magazine comprises,
 3. openingsextending through said retainer plate between said chamber and saidslots through which such fluid may pass into said slots, and
 3. controlstructure for regulating introduction of supporting fluid into saidpassages in accordance with sequential indexing of said magazine by saidindexing means.
 3. vacuum structure for maintaining an article on saidpickup arm when said arm is presented to such article, and
 3. a driverod engaged with such support base which is actuatable in predeterminedsequential increments determined by the spacing between adjacentarticles in such magazine, and
 3. control structure for regulatingintroduction of supporting fluid into and through said track structurein accordance with sequential indexing of said magazines by saidindexing means associated with the respective magazines.
 4. power sourcemechanism for sequentially actuating said rod to effect incrementalmovement of said rod and such support base therewith.
 4. The apparatusof claim 3 in which the respective movable rods engaged with therespective supply and discharge magazine support bases are movable bytheir associated power source mechanisms in opposite directions so thatone of said magazines is indexed sequentially upwardly and the other ofsaid magazines is indexed sequentially downwardly.
 4. means for movingsaid plate structure and said arm therewith sequentially toward and awayfrom said station during picking up and transfer of articles relativethereto.
 4. a series of bars received in and substantially filling saidslots,
 4. power source mechanism for sequentially actuating each saidrod to effect incremental movement of such rod and its associatedsupport base therewith.
 4. The passages of said second series beingconnected with said structure for introducing fluid, wherebybidirectional article moving capability is imparted to said trackstructure.
 5. the upper surfaces of said bars lying generally inalignment with said upper surface of said retainer plate and joiningtherewith in defining a bearing surface over which said articles arepassable,
 5. structure mounting said pickup arm for selective up anddown movement relative to said plate to facilitate pickup and dischargeof articles by said arm, and
 5. The apparatus of claim 1 in which eachsaid transfer means comprises
 6. mechanism for actuating said mountingstructure in predetermined timed sequence to elevate and retract saidpickup arm during article pickup and discharge.
 6. The apparatus ofclaim 5 in which said transfer means further includes
 6. each of saidbars having a. a series of spaced grooves formed in a side face thereof,b. said grooves being formed to extend at a predetermined angularinclination relative to the longitudinal axis of such bar.
 7. Incombination in an apparatus for handling articles, such as siliconwafers, A. a magazine for receiving a quantity of said articles thereinin stacked relationship,
 8. The apparatus of claim 7 in which saidfluid-bearing means comprises,
 9. The apparatus of claim 8 in which saidpassages in said track structure are directionally oriented to movearticles inwardly into said magazine when fluid passes through saidpassages.
 10. The apparatus of claim 8 in which said passages in saidtrack structure are directionally oriented to move articles outwardlyfrom said magazine when fluid passes through said passages.
 11. Theapparatus of claim 8 in which said track structure further comprises c.at least two series of said directional fluid passages, d. one of saidseries of passages being directionally oriented to move articles in afirst direction relative to said mAgazine, e. the other of said seriesof passages being directionally oriented to move articles in anotherdirection relative to said magazine, and in which said control structurefor regulating introduction of supporting fluid into said passagescomprises a. structure permitting introduction of said supporting fluidselectively into a predetermined one or the other of said series ofpassages.
 12. The apparatus of claim 8 in which each of said passages isgenerally arcuately curved in configuration from the lower end thereoftoward the upper end thereof which opens to the upper surface of saidtrack structures.
 13. The apparatus of claim 12 in which each of saidpassages is larger at the lower end thereof than the upper end thereof,whereby a curved nozzle configuration is imparted thereto.
 14. Theapparatus of claim 7 in which said fluid-bearing means comprises a trackstructure which includes
 15. The apparatus of claim 14 in which each ofsaid bars further comprises c. another series of spaced grooves formedin the other side face of said bar, d. said other series of grooves alsobeing formed to extend at a predetermined angular inclination relativeto the longitudinal axis of said bar.
 16. The apparatus of claim 15 inwhich e. the series of grooves along said one side face of said barextend in an inclination which is generally opposite to the inclinationat which the series of grooves extend along said other side face,whereby bidirectional article movement capability is imparted to saidfluid-bearing means.
 17. The apparatus of claim 7 in which said magazinecomprises,
 18. The apparatus of claim 7 in which said means for indexingsaid magazine comprises, a. guide structure for said magazine supportbase, b. a drive rod engaged with said support base which is actuatablein predetermined sequential increments determined by the spacing betweenadjacent slots in which articles are positioned in said magazine, and c.power source mechanism for sequentially actuating said rod to effectincremental movement of said rod and said support base therewith. 19.The apparatus of claim 18 in which said drive rod is threadedly engagedwith said support base, and in which said power source mechanismcomprises, i. a drive motor for rotating sad rod a predetermined amountfollowing movement of each article relative to said magazine so thatsaid rod will index said support base one position to present anotherarticle receiving slot to said fluid-bearing means.
 20. The apparatus ofclaim 18 which further includes E. control means for regulatingoperation of said power source mechanism comprising,
 21. In combinationin an apparatus for handling and treating articles, A. a supply magazinefor a quantity of said articles, B. fluid-bearing means for withdrawingarticles individually from said supply magazine, C. means for treatingarticles presented thereto in sequence, D. transfer means for receivingarticles with drawn from said magazine to move the same in sequence tosaid treating means and from said treating means following treatmentthereof, E. a discharge magazine for receiving a quantity of treatedarticles, and F. fluid-bearing means for receiving articles in sequencefrom said transfer means and for introducing such articles in sequenceinto said discharge magazine.
 22. The combination of claim 21 whichfurther includes G. means cooperable with said first and secondmentioned fluid-bearing means for sequentially indexing said supplymagazine and said discharge magazine in response to movement of saidarticles sequentially from said supply magazine and into said dischargemagazine.
 23. The apparatus of claim 21 in which each said supplymagazine and said discharge magazine comprises,
 24. The apparatus ofclaim 21 in which each of sad means for indexing said supply magazineand said discharge magazine comprises,
 25. The apparatus of claim 24 inwhich the respective movable drive rods engaged with the respectivesupply and discharge magazine support bases are movable by theirassociated power source mechanisms in opposite directions so that one ofsaid magazines is indexable sequentially upwardly and the other of saidmagazines is indexable sequentially downwardly.
 26. The apparatus ofclaim 24 in which each said drive rod is threadedly engaged with itsassociated support base, and in which each said power source mechanismcomprises,
 27. The apparatus of claim 24 which further includes G.control means for regulating operation of each said power sourcemechanism comprising,
 28. Fluid-bearing means for transporting articlesfrom one station to another comprising A. a track structure whichincludes
 29. The fluid-bearing means of claim 28 in which said structurefor introducing fluid into said passages includes
 30. The fluid-bearingmeans of claim 28 in which said track structure further includes
 31. Thefluid-bearing means of claim 28 in which each of said passages isdefined by a curved tapered groove the lower end of which is larger thanthe upper end thereof, whereby a curved nozzle configuration is impartedthereto.
 32. Fluid-bearing track structure for transporting articlesfrom one station to another comprising A. a retainer plate having aseries of generally parallel slots formed in an upper surface thereof,B. a chamber formed in a lower surface of said retainer plate incommunication with a source of article supporting fluid, C. openingsextending through said retainer plate between said chamber and saidslots through which such fluid may pass into said slots, and D. a seriesof bars received in and substantially filling said slots,
 33. The trackstructure of claim 32 in which each of said bars further includes c.another series of spaced grooves formed in the other side face of saidbar, d. said other series of grooves also being formed to open onto saidupper surface at a predetermined angular inclination relative to thelongitudinal axis of said bar.
 34. The track structure of claim 33 inwhich e. the series of grooves along said one side face of said barextends at an inclination which is generally opposite to the inclinationat which the series of grooves extend along said other side face,whereby bidirectional article movement capability is imparted to saidtrack structure.
 35. The track structure of claim 32 in which each ofsaid grooves is formed with a curved tapered nozzle shaped configurationwhich is deeper and wider at the lower end thereof that at its upper endwhich opens onto the upper surface of said retainer plate.
 36. Means fororienting the center of a generally flat article comprising A. a shallowdish having a concave upper surface onto which an article to be centeredis deposited, B. a plurality of fluid passages extending through saiddish and surrounding the center of said upper surface, C. structureconnecting said passages with a source of supply of article supportingfluid, and D. mechanism for effecting intermittent pulsating flow ofsaid fluid inTo and through said passages onto said dish upper surfaceto produce generally reciprocating movement of an article on saidsurface until such article is positioned with its center overlying saidcenter of said surface.
 37. The means of claim 36 which furthercomprises E. a bore extending through said dish,
 38. The means of claim37 which further includes H. vacuum structure in conjunction with saidcentering pin for maintaining an article thereon as said pin is elevatedto present such article to such pickup and transfer means.
 39. A methodof handling articles, such as generally flat silicon wafers, to orienttheir centers in a predetermined location comprising, A. providing acentering dish having a shallow concave upper surface and air passagesextending therethrough opening onto said upper surface, B. positioningan article to be centered on said upper surface, C. introducing asupporting fluid through said passages into contact with said article onsaid upper surface, and D. causing the flow of said supporting fluid topulse as it passes into said upper surface to intermittently raise andlower said article and in so doing to move said article toward thecenter of said surface.
 40. The method of claim 39 which furtherincludes E. elevating said article above said upper surface after thecenter of said article has been aligned with the center of said surface,and F. retaining the centered orientation of said article during suchelevation until the article is engaged for transfer to another stationfor subsequent treatment.
 41. A method of withdrawing articles insequence from a supply magazine in which a plurality of such articlesare positioned comprising A. providing a fluid-bearing track structureadjacent said magazine having a portion thereof which extends inunderlying relationship relative to the articles in said magazine, B.indexing said magazine to bring successive articles into a withdrawingposition which is generally in alignment with said portion of said trackstructure, C. introducing article supporting fluid through said trackstructure into engagement with each successive article located in saidwithdrawing position, and D. imparting outward directional flow to saidfluid with said track structure to cause said fluid to move each saidsuccessive article from said magazine.
 42. A method of inserting aplurality of articles in sequence into a magazine comprising A.providing a fluid-bearing track structure adjacent sad magazine having aportion thereof which extends in underlying relationship relative tosaid magazine, B. positioning articles in sequence upon said trackstructure, C. introducing article supporting fluid upwardly through saidtrack structure into engagement with each successive article positionedthereon, D. imparting inward directional flow to said fluid with saidtrack structure to cause said fluid to move each said successive articleinto said magazine, and E. indexing said magazine following insertion ofan article thereinto to prepare said magazine to receive a subsequentarticle.
 43. A method of handling articles for movement between twostations comprising A. providing a fluid-bearing track structure whichextends between said stations, B. placing an article on said trackstructure, C. introducing article supporting fluid through said trackstructure into engagement with said article, D. imparting directionalflow to said fluid with said track strucTure to cause said fluid to movesaid article from one of said stations to the other, and E. followingtreatment of said article at said other station imparting reversedirectional flow to said fluid with said track structure to cause saidfluid to move said article back from said other station to said onestation.
 44. In combination in an apparatus for handling articles, suchas silicon wafers, A. an indexable magazine for receiving a quantity ofsaid articles therein in stacked spaced relationship,
 45. The apparatusof claim 44 in which said magazine comprises,
 46. The apparatus of claim44 in which said means for indexing said magazine comprises, a. guidestructure for said magazine support base, b. a drive rod engaged withsaid support base which is actuatable in a predetermined sequentialincrements determined by the spacing between adjacent slots in whicharticles are positioned in said magazine, and c. power source mechanismfor sequentially actuating said rod to effect incremental movement ofsaid rod and said support base therewith.
 47. The apparatus of claim 46in which said drive rod is threadedly engaged with said support base,and in which said power source mechanism comprises,
 48. The apparatus ofclaim 46 in which said indexing means further includes d. control meansfor regulating operation of said power source mechanism comprising i. asensor past which each article passes as it is moved relative to saidmagazine, ii. each such article causing said sensor to transmit anindexing control signal to said power source mechanism.
 49. Incombination in an apparatus for handling and treating generally flatarticles, such as silicon wafers, without manual handling, A. centeringmeans to which articles are presented in sequence for orienting eacharticle presented thereto with its center in a predetermined locationcomprising,
 50. A method of handling and treating articles, such assilicon wafers, without manual handling, comprising A. providing asupply of articles at a feed station, B. sequentially withdrawingindividual articles from said supply and placing the same in sequence ona fluid-bearing track structure adjacent said supply, C. moving suchwithdrawn articles in sequence to a centering station on saidfluid-bearing track structure, D. locating the centers of such withdrawnarticles in sequence at said centering station, E. transferring suchcentered articles in sequence to a treating station, F. positioning saidcentered articles in sequence at said treating station in apredetermined orientation for treatment at such station, and G. placingsuch articles following treatment thereof in sequence on a fluid-bearingtrack structure and transferring such articles on said last mentionedfluid-bearing track structure to a discharge station.
 51. A method ofwithdrawing articles in sequence from a supply magazine in which aplurality of such articles are positioned comprising A. providing afluid-bearing track structure adjacent said magazine having a portionthereof adjacent to the articles in said magazine, B. indexing saidmagazine to bring successive articles into a withdrawing position whichis generally in alignment with said track structure, C. withdrawingarticles in sequence from said magazine and placing the same on saidtrack structure, D. introducing article supporting fluid through saidtrack structure into engagement with each successive article locatedthereon, and E. imparting outward directional flow to said fluid withsaid track structure to cause said fluid to move each said successivearticle away from said magazine.
 52. A method of inserting a pluralityof articles in sequence into a magazine comprising A. providing afluid-bearing track structure adjacent said magazine having a portionthereof adjacent to said magazine, B. positioning articles in sequenceupon said track structure, C. introducing article supporting fluidupwardly through said track structure into engagement with eachsuccessive article positioned thereon, D. indexing said magazine toposition the same to receive an article therein from said trackstructure, E. imparting inward directional flow to said fluid with saidtrack structure to cause said fluid to move each said successive articleplaced thereon into said magazine, and F. indexing said magazinefollowing insertion of an article thereinto to prepare said magazine toreceive therein a subsequent article.